var Exp = /[\da-zA-Z]/
function yanzhen(char) {
    return Exp.test(char)
}

function ishuiwenchuan (s) {
  var left = 0,right =s.length - 1;
  while (left < right) {
    var leftChar = s[left];
    var rightChar = s[right];
    if(!yanzhen(leftChar)){
      left++;
    }else if(!yanzhen(rightChar)){
      righ--;
    }else if(leftChar!==rightChar){
      return false;
    }else{
      left++;
      right--;
    }
  }
  return true;

}
 var res = ishuiwenchuan("123321")
 console.log(res)
 var a = [1,2] + {a:2};
 console.log(typeof a)
  